Theodor W. Adorno's defence of modern art in Aesthetic Theory and other writings is well known, as is his scathing attack on jazz. Less well known is his critique of monochromatic painting. This article first sketches the stakes and terms of this critique in relation to Clement Greenberg's dismissal of much monochromatic or near-monochromatic painting, before moving on to an analysis of Adorno's position. For the purposes of this analysis, Yves Klein's IKB 79 serves as a test case.